The present application claims priority under 35 U.S.C. xc2xa7119 of German Patent Application No. 199 30 088.7, filed on Jun. 30, 1999, the disclosure of which is expressly incorporated by reference herein in its entirety.
1. Field of the Invention
The present invention relates to a hydrocyclone for removing foreign substances from a liquid which includes at least one inlet for the liquid to be cleaned, at least one accepted stock outlet for the cleaned liquid, and at least one reject opening for foreign substances, which has at least one stoppage-hazard zone.
2. Discussion of Background Information
As is generally known, hydrocyclones are used for concentrating and draining off liquids containing foreign substances using strong centrifugal forces. They are frequently used in the removal of small metal parts, glass splinters, and sand from fibrous stock suspensions. As a result of the accumulation of foreign substances in specific areas of the hydrocyclone, stoppages are to be expected if all operating parameters are not set optimally. However, due to frequently changing operating conditions, such as the dirt load, the occurrence of stoppages cannot always be prevented. For this reason, a hydrocyclone must, as a rule, be expected to have a stoppage-hazard zone. The formation of stoppages has at least two considerable disadvantages: The hydrocyclone will then no longer fulfill its task, i.e., will no longer be able to remove foreign substances; and in some cases, high local wear occurs on the hydrocyclone that is caused by the heavy parts rotating at one location and thus abrading the wall of the hydrocyclone.
Continuous monitoring of the hydrocyclone is required in order to avoid the occurrence of stoppages or at least to shorten this undesired state. However, because many facilities contain a large number of hydrocyclones, this can be expensive.
A process for monitoring a cyclone is disclosed, e.g., in CH 681360 A, which discloses that the surface temperature on the cyclone is determined and compared to that of the ambient temperature. In the case of stoppages, these two temperatures approach each other. An evaluation circuit is informed of the stoppage via a data line so that it can emit a warning and/or adjustment signal. This process is to be operated only with a plurality of measuring transducers and corresponding regulating and adjustment effort.
The present invention provides a hydrocyclone in which it is possible to discover and eliminate stoppages in the short term using the simplest manner.
Further, the present invention includes a color layer which is attached on the exterior wall of the hydrocyclone whose appearance changes with different temperatures.
In the case of hydrocyclones equipped according to the invention, a layer is provided at critical locations that changes its appearance, e.g., its color, in accordance with temperature changes in the area of interest. In this manner, the present invention utilizes the fact that critical accumulation of substances that may cause stoppages, e.g., foreign substances, produces or creates temperature changes. The reason is that the temperature of the liquid to be cleaned almost always deviates from the ambient temperature. For example, the temperature is higher at locations at which the liquid is flowing by the wall of the flow device, thereby producing heat. As a consequence, an approximately uniform temperature adjusts or occurs during the undisturbed operation of the flow device. However, if the accumulation of foreign substances becomes so great that the flow is partially brought to a standstill, i.e., a stoppage is imminent, the flow device begins to cool at this location toward the ambient temperature. As a result, a local temperature change can be viewed as an indicator of a stoppage, e.g., that has begun or that has already occurred. In this way, it is possible to prevent or quickly eliminate operating malfunctions. Tests determine the to-be-prescribed extent of the temperature deviation at which a critical accumulation of foreign substances is present. It depends, among other things, on the level and constancy of the temperature of the liquid in the flow device.
In this manner, it is very easy to monitor an entire battery of hydrocyclones. No lines are required for the power supply or measuring data and measuring strips that change color as a function of temperature are inexpensive and easy to handle. Such measuring strip are used as thermometers, which, though easy to read, are often slow-reacting and imprecise. However, they are ideal for the instant invention to provide xe2x80x9cat a glancexe2x80x9d detection. This is particularly advantageous with the conventionally large number of hydrocyclones in a facility. Moreover, it is not necessary to determine or detect an exact numerical value of the temperature.
While somewhat more expensive, an optical remote display of the changes, e.g., in a control room, can be provided with a monitoring camera.
The present invention is directed to a hydrocyclone for removing foreign substances from a liquid to be cleaned. The hydrocyclone includes at least one inlet for the liquid to be cleaned, at least one accepted stock outlet for the cleaned liquid, and at least one reject opening for foreign substances removed from the liquid to be cleaned. The at least one reject opening includes at least one stoppage-hazard zone, and a color layer is coupled to an exterior wall of the hydrocyclone. The color layer changes appearance in accordance with different temperatures.
In accordance with a feature of the instant invention, the at least one reject opening can be arranged for discharging heavy parts. Alternatively, the at least one reject opening can be arranged for discharging light parts.
According to another feature of the invention, the color layer can change its color as it is cooled.
In accordance with still another feature of the present invention, the color layer can change its color as a warning.
According to a further feature of the invention, the color layer can be coupled in a vicinity of the at least one reject opening. Moreover, the color layer can be coupled to a connection line downstream of the at least one reject opening.
Moreover, the color layer can be adapted to change its appearance to indicate a temperature change of between about 25 and 40xc2x0 C.
The color layer can include a foil. Further, the foil can be glued onto the exterior wall.
The hydrocyclone can be adapted for separating foreign substances from a papermaking fiber suspension whose temperature deviates from the ambient temperature.
Further, an adjusting device may be coupled to the at least one reject opening. A flow cross-section of the at least one reject opening can be enlarged by the adjusting device.
Still further, the color layer can be arranged to change color as a temperature at the exterior wall decreases. The color layer can be adapted to change color in response to a temperature change of between about 25 and 40xc2x0 C.
The present invention is directed to a hydrocyclone facility that includes at least ten simultaneously operated hydrocyclones. The hydrocyclones include a color layer coupled to exterior walls of the hydrocyclones, such that the color layer changes its appearance in accordance with a changing temperature difference between the exterior wall and an ambient temperature.
The present invention is directed to a process for removing foreign substances from a liquid to be cleaned. The process includes introducing the liquid to be cleaned into a hydrocyclone through at least one inlet, discharging cleaned liquid from the hydrocyclone through at least one accepted stock outlet, and discharging the foreign substances from the hydrocyclone through at least one reject opening. The process also includes detecting one of a potential and an actual stoppage in a stoppage-hazard zone of the at least one reject opening by monitoring a color change of a color layer coupled to an exterior wall of the hydrocyclone.
According to a feature of the invention, the color layer can be adapted to change color in accordance with a changing temperature difference between the exterior wall of the hydrocyclone and an ambient temperature.
In accordance with another feature of the present invention, the color layer can be adapted to change color when an accumulation of foreign substances substantially prevents the flow of the liquid to be cleaned in the stoppage-hazard zone.
Moreover, the color layer can be coupled to a conical portion of the hydrocyclone which forms at least a portion of the at least one reject opening.
Further, the stoppage-hazard zone may be a light substance pipe coupled to a deposition pot.
The process can also include discharging heavy parts through the at least one rejects opening. In this manner, the color layer may be coupled to a conical portion of the at least one reject opening. In an alternative arrangement, the process can include discharging light parts through the at least one rejects opening. In this way, the color layer may be coupled to a conical portion of the at least one reject opening. Moreover, the color layer may be coupled to a light substance pipe, which is coupled to a deposition pot.
According to yet another feature of the instant invention, the process can further include enlarging a cross-section of the at least one reject opening in accordance with the appearance of the color layer.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.